/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.scripting.config;

import java.util.List;

import org.w3c.dom.Element;

import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionDefaults;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.BeanDefinitionParserDelegate;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.beans.factory.xml.XmlReaderContext;
import org.springframework.lang.Nullable;
import org.springframework.scripting.support.ScriptFactoryPostProcessor;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.DomUtils;

/**
 * BeanDefinitionParser implementation for the '{@code <lang:groovy/>}',
 * '{@code <lang:std/>}' and '{@code <lang:bsh/>}' tags.
 * Allows for objects written using dynamic languages to be easily exposed with
 * the {@link org.springframework.beans.factory.BeanFactory}.
 *
 * <p>The script for each object can be specified either as a reference to the
 * resource containing it (using the '{@code script-source}' attribute) or inline
 * in the XML configuration itself (using the '{@code inline-script}' attribute.
 *
 * <p>By default, dynamic objects created with these tags are <strong>not</strong>
 * refreshable. To enable refreshing, specify the refresh check delay for each
 * object (in milliseconds) using the '{@code refresh-check-delay}' attribute.
 *
 * @author Rob Harrop
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Mark Fisher
 * @since 2.0
 */
class ScriptBeanDefinitionParser extends AbstractBeanDefinitionParser {

    private static final String ENGINE_ATTRIBUTE = "engine";

    private static final String SCRIPT_SOURCE_ATTRIBUTE = "script-source";

    private static final String INLINE_SCRIPT_ELEMENT = "inline-script";

    private static final String SCOPE_ATTRIBUTE = "scope";

    private static final String AUTOWIRE_ATTRIBUTE = "autowire";

    private static final String DEPENDS_ON_ATTRIBUTE = "depends-on";

    private static final String INIT_METHOD_ATTRIBUTE = "init-method";

    private static final String DESTROY_METHOD_ATTRIBUTE = "destroy-method";

    private static final String SCRIPT_INTERFACES_ATTRIBUTE = "script-interfaces";

    private static final String REFRESH_CHECK_DELAY_ATTRIBUTE = "refresh-check-delay";

    private static final String PROXY_TARGET_CLASS_ATTRIBUTE = "proxy-target-class";

    private static final String CUSTOMIZER_REF_ATTRIBUTE = "customizer-ref";


    /**
     * The {@link org.springframework.scripting.ScriptFactory} class that this
     * parser instance will create bean definitions for.
     */
    private final String scriptFactoryClassName;


    /**
     * Create a new instance of this parser, creating bean definitions for the
     * supplied {@link org.springframework.scripting.ScriptFactory} class.
     *
     * @param scriptFactoryClassName the ScriptFactory class to operate on
     */
    public ScriptBeanDefinitionParser(String scriptFactoryClassName) {
        this.scriptFactoryClassName = scriptFactoryClassName;
    }


    /**
     * Parses the dynamic object element and returns the resulting bean definition.
     * Registers a {@link ScriptFactoryPostProcessor} if needed.
     */
    @Override
    @SuppressWarnings("deprecation")
    @Nullable
    protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
        // Engine attribute only supported for <lang:std>
        String engine = element.getAttribute(ENGINE_ATTRIBUTE);

        // Resolve the script source.
        String value = resolveScriptSource(element, parserContext.getReaderContext());
        if (value == null) {
            return null;
        }

        // Set up infrastructure.
        LangNamespaceUtils.registerScriptFactoryPostProcessorIfNecessary(parserContext.getRegistry());

        // Create script factory bean definition.
        GenericBeanDefinition bd = new GenericBeanDefinition();
        bd.setBeanClassName(this.scriptFactoryClassName);
        bd.setSource(parserContext.extractSource(element));
        bd.setAttribute(ScriptFactoryPostProcessor.LANGUAGE_ATTRIBUTE, element.getLocalName());

        // Determine bean scope.
        String scope = element.getAttribute(SCOPE_ATTRIBUTE);
        if (StringUtils.hasLength(scope)) {
            bd.setScope(scope);
        }

        // Determine autowire mode.
        String autowire = element.getAttribute(AUTOWIRE_ATTRIBUTE);
        int autowireMode = parserContext.getDelegate().getAutowireMode(autowire);
        // Only "byType" and "byName" supported, but maybe other default inherited...
        if (autowireMode == AbstractBeanDefinition.AUTOWIRE_AUTODETECT) {
            autowireMode = AbstractBeanDefinition.AUTOWIRE_BY_TYPE;
        }
        else if (autowireMode == AbstractBeanDefinition.AUTOWIRE_CONSTRUCTOR) {
            autowireMode = AbstractBeanDefinition.AUTOWIRE_NO;
        }
        bd.setAutowireMode(autowireMode);

        // Parse depends-on list of bean names.
        String dependsOn = element.getAttribute(DEPENDS_ON_ATTRIBUTE);
        if (StringUtils.hasLength(dependsOn)) {
            bd.setDependsOn(StringUtils.tokenizeToStringArray(
                    dependsOn, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS));
        }

        // Retrieve the defaults for bean definitions within this parser context
        BeanDefinitionDefaults beanDefinitionDefaults = parserContext.getDelegate().getBeanDefinitionDefaults();

        // Determine init method and destroy method.
        String initMethod = element.getAttribute(INIT_METHOD_ATTRIBUTE);
        if (StringUtils.hasLength(initMethod)) {
            bd.setInitMethodName(initMethod);
        }
        else if (beanDefinitionDefaults.getInitMethodName() != null) {
            bd.setInitMethodName(beanDefinitionDefaults.getInitMethodName());
        }

        if (element.hasAttribute(DESTROY_METHOD_ATTRIBUTE)) {
            String destroyMethod = element.getAttribute(DESTROY_METHOD_ATTRIBUTE);
            bd.setDestroyMethodName(destroyMethod);
        }
        else if (beanDefinitionDefaults.getDestroyMethodName() != null) {
            bd.setDestroyMethodName(beanDefinitionDefaults.getDestroyMethodName());
        }

        // Attach any refresh metadata.
        String refreshCheckDelay = element.getAttribute(REFRESH_CHECK_DELAY_ATTRIBUTE);
        if (StringUtils.hasText(refreshCheckDelay)) {
            bd.setAttribute(ScriptFactoryPostProcessor.REFRESH_CHECK_DELAY_ATTRIBUTE, Long.valueOf(refreshCheckDelay));
        }

        // Attach any proxy target class metadata.
        String proxyTargetClass = element.getAttribute(PROXY_TARGET_CLASS_ATTRIBUTE);
        if (StringUtils.hasText(proxyTargetClass)) {
            bd.setAttribute(ScriptFactoryPostProcessor.PROXY_TARGET_CLASS_ATTRIBUTE, Boolean.valueOf(proxyTargetClass));
        }

        // Add constructor arguments.
        ConstructorArgumentValues cav = bd.getConstructorArgumentValues();
        int constructorArgNum = 0;
        if (StringUtils.hasLength(engine)) {
            cav.addIndexedArgumentValue(constructorArgNum++, engine);
        }
        cav.addIndexedArgumentValue(constructorArgNum++, value);
        if (element.hasAttribute(SCRIPT_INTERFACES_ATTRIBUTE)) {
            cav.addIndexedArgumentValue(
                    constructorArgNum++, element.getAttribute(SCRIPT_INTERFACES_ATTRIBUTE), "java.lang.Class[]");
        }

        // This is used for Groovy. It's a bean reference to a customizer bean.
        if (element.hasAttribute(CUSTOMIZER_REF_ATTRIBUTE)) {
            String customizerBeanName = element.getAttribute(CUSTOMIZER_REF_ATTRIBUTE);
            if (!StringUtils.hasText(customizerBeanName)) {
                parserContext.getReaderContext().error("Attribute 'customizer-ref' has empty value", element);
            }
            else {
                cav.addIndexedArgumentValue(constructorArgNum++, new RuntimeBeanReference(customizerBeanName));
            }
        }

        // Add any property definitions that need adding.
        parserContext.getDelegate().parsePropertyElements(element, bd);

        return bd;
    }

    /**
     * Resolves the script source from either the '{@code script-source}' attribute or
     * the '{@code inline-script}' element. Logs and {@link XmlReaderContext#error} and
     * returns {@code null} if neither or both of these values are specified.
     */
    @Nullable
    private String resolveScriptSource(Element element, XmlReaderContext readerContext) {
        boolean hasScriptSource = element.hasAttribute(SCRIPT_SOURCE_ATTRIBUTE);
        List<Element> elements = DomUtils.getChildElementsByTagName(element, INLINE_SCRIPT_ELEMENT);
        if (hasScriptSource && !elements.isEmpty()) {
            readerContext.error("Only one of 'script-source' and 'inline-script' should be specified.", element);
            return null;
        }
        else if (hasScriptSource) {
            return element.getAttribute(SCRIPT_SOURCE_ATTRIBUTE);
        }
        else if (!elements.isEmpty()) {
            Element inlineElement = elements.get(0);
            return "inline:" + DomUtils.getTextValue(inlineElement);
        }
        else {
            readerContext.error("Must specify either 'script-source' or 'inline-script'.", element);
            return null;
        }
    }

    /**
     * Scripted beans may be anonymous as well.
     */
    @Override
    protected boolean shouldGenerateIdAsFallback() {
        return true;
    }

}
